U.S. authorities put alleged Boston bomber Tamerlan Tsarnaev on two separate watch lists in 2011 after Russian security agencies twice reached out to their American counterparts, raising new questions about missed opportunities to prevent the attack.

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Police at a service Wednesday in Cambridge, Mass., for MIT Officer Sean Collier, allegedly killed by the Tsarnaev brothers.
Associated Press

Russian officials contacted the Federal Bureau of Investigation in March 2011, then reached out to the Central Intelligence Agency in September of that year, citing concerns Mr. Tsarnaev might have been associating with extremists, according to U.S. officials.

The FBI has said it interviewed Mr. Tsarnaev and conducted a threat assessment, but found nothing "derogatory" that could prompt further investigation. A U.S. law-enforcement official said the case was closed after three months, after the FBI asked Russian counterparts for additional information, but received none.

U.S. officials said Wednesday that at the request of the CIA, Mr. Tsarnaev was added to a broad database called Terrorist Identities Datamart Environment, which holds hundreds of thousands of names flagged by multiple U.S. security agencies.

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Because Mr. Tsarnaev was a permanent resident of the U.S., the CIA alerted relevant domestic agencies, including the FBI, "specifying that Tamerlan may be of interest to them," a U.S. intelligence official said.

The information Russia provided the CIA was "identical" to what it gave the FBI in March 2011, another U.S. intelligence official said. It included two possible dates of birth for Mr. Tsarnaev, his name spelled in Cyrillic letters and a transliteration of the name that was different from what Mr. Tsarnaev used in official U.S. records.

The apparent communication snags may at least partly be explained by the sometimes uneasy relationship between U.S. and Russian intelligence and law-enforcement agencies.

Even since the bombings, information sharing between Russian and U.S. agencies has been "a challenge," a congressional aide briefed on the matter said.

The FBI's earlier contact with Mr. Tsarnaev already had caused his name to be put in another database, called TECS, which is used by U.S. police and national-security agencies, two law-enforcement officials said.

Homeland Security Secretary Janet Napolitano said Tuesday that U.S. authorities were aware when Mr. Tsarnaev traveled to Russia in January 2012, because the system "pinged" when his name was entered in flight data.

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Because the FBI's earlier inquiry had been concluded without finding any terrorism concerns, there was no obvious reason to bar him from flying, U.S. officials said. Officials said the FBI and other agencies did as much as they legally were authorized, given the limited information passed on by Russian authorities.

The FBI and CIA decisions to add Mr. Tsarnaev to passive U.S. security databases are routine and intended to send alerts to other security agencies. Taking more investigative action, or putting him on a no-fly list, could have raised constitutional questions given the limited grounds for suspicion at the time, they said.

Rep. C.A. Dutch Ruppersberger (D., Md.), the top Democrat on the House intelligence committee, on Wednesday made a plea for more Russian assistance. Mr. Ruppersberger said the Russians didn't detail their concerns when they flagged Tamerlan to U.S. agencies. "They just said this person could be a potential threat," he said. Mr. Ruppersberger said the FBI followed up three separate times with Russian authorities and got no response.

Thus far, questions from Congress about whether U.S. agencies erred have been relatively muted, although some lawmakers have called for hearings into possible intelligence failures. One member of the House intelligence committee, Rep. Jim Himes (R., Conn.), briefed on the Boston investigation Wednesday, said the case wasn't raising concerns about intelligence agencies failing to share information., a process often called "stovepiping"

More details emerged Wednesday about the bombing. Investigators believe the bombs were detonated using controls from remote-control model cars, two U.S. officials said. They are believed to have radio signals that reach only short distances, unlike more-sophisticated cellphone-activated detonators, the officials said.

Mr. Ruppersberger said the brothers drew from a bomb recipe in Inspire, a magazine published by al Qaeda's Yemen branch. He said they adopted the type of "under the radar strategy" advocated by the group in which jihadi sympathizers who wouldn't be seen as suspect by U.S. authorities carry out attacks. Officials say, however, there's no evidence at this time that the attacks were directed by al Qaeda or any foreign group.

Mr. Tsarnaev's brother, Dzhokhar, 19 years old, identified by U.S. prosecutors as the other bomber in the April 15 attacks, has told interrogators in handwritten answers that the brothers acted as jihadists and out of Muslim religious anger at the U.S.

Investigators didn't find a gun in the boat that Dzhokhar Tsarnaev was hiding in when captured Friday, U.S. law enforcement officials said. Police initially said there was a shootout between officers and the suspect.

Meanwhile, New York Police Commissioner Raymond Kelly said Mr. Tsarnaev and his younger brother, Dzhokhar, planned to "party" in New York after the attack. Mr. Kelly said the detail emerged from the hospital interrogation of 19-year-old Dzhokhar, who was charged this week in connection with the April 15 bombings that killed three people and injured more than 200.

The police commissioner said there is no evidence the suspects planned attacks in New York.

While the brothers didn't appear to have any intimate connection to New York, Mr. Kelly said investigators in Boston and New York are looking into at least one visit by Dzhokhar Tsarnaev to the city last November.

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